Bug#481177: openssh-server: randomise size of rsa host keys
Package: openssh-server
Version: 1:4.7p1-9
Severity: wishlist
Tags: patch
Hi,
Given that rainbow tables for vulnerable keys are
predicated on the size of the key, would you consider
randomizing the length of the host RSA key, to protect
against future exploits?
Something like this:
--- debian/openssh-server.postinst~ 2008-05-14 11:45:59.000000000 +0100
+++ debian/openssh-server.postinst 2008-05-14 11:48:31.000000000 +0100
@@ -172,12 +172,13 @@
create_keys() {
hostkeys="$(host_keys_required)"
+ bits=$(expr 2048 + $(expr $RANDOM % 64))
create_key "Creating SSH1 key; this may take some time ..." \
"$hostkeys" /etc/ssh/ssh_host_key -t rsa1
create_key "Creating SSH2 RSA key; this may take some time ..." \
- "$hostkeys" /etc/ssh/ssh_host_rsa_key -t rsa
+ "$hostkeys" /etc/ssh/ssh_host_rsa_key -t rsa -b "$bits"
create_key "Creating SSH2 DSA key; this may take some time ..." \
"$hostkeys" /etc/ssh/ssh_host_dsa_key -t dsa
}
-- System Information:
Debian Release: lenny/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: i386 (i686)
Kernel: Linux 2.6.24-1-486
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages openssh-server depends on:
ii adduser 3.107 add and remove users and groups
ii debconf [debconf-2.0] 1.5.21 Debian configuration management sy
ii dpkg 1.14.19 package maintenance system for Deb
ii libc6 2.7-11 GNU C Library: Shared libraries
ii libcomerr2 1.40.8-2 common error description library
ii libkrb53 1.6.dfsg.3-2 MIT Kerberos runtime libraries
ii libpam-modules 0.99.7.1-6 Pluggable Authentication Modules f
ii libpam-runtime 0.99.7.1-6 Runtime support for the PAM librar
ii libpam0g 0.99.7.1-6 Pluggable Authentication Modules l
ii libselinux1 2.0.59-1 SELinux shared libraries
ii libssl0.9.8 0.9.8g-10 SSL shared libraries
ii libwrap0 7.6.q-15 Wietse Venema's TCP wrappers libra
ii lsb-base 3.2-8 Linux Standard Base 3.2 init scrip
ii openssh-blacklist 0.1.0 list of blacklisted OpenSSH RSA an
ii openssh-client 1:4.7p1-9 secure shell client, an rlogin/rsh
ii zlib1g 1:1.2.3.3.dfsg-12 compression library - runtime
Versions of packages openssh-server recommends:
ii xauth 1:1.0.3-1 X authentication utility
-- debconf information:
ssh/vulnerable_host_keys:
ssh/new_config: true
* ssh/use_old_init_script: true
ssh/disable_cr_auth: false
ssh/encrypted_host_key_but_no_keygen:
--
Jon Dowland
ISS UNIX Team
Reply to: